1. Field of the Invention
This invention relates to bending rolls, specifically for adjustable bending rolls utilized in coil boxes.
2. Prior Art
The coil box is a device used in hot strip mills to coil transfer bars, or strips, prior to entry of the strip into a finishing train. One of the most critical functions during the operation of a coil box is the initial coil formation, otherwise known as the first wrap. Early coil boxes possessed a sliding frame which located an upper pair of bending rolls for various strip thicknesses; setup adjustments of the set of bending rolls were performed by raising or lowering the upper bending roll frame. This adjusted both the two upper bending rolls equally and there was no provision for different adjustments of the individual upper bending rolls. Consequently, the location of the strip impact against a forming roll was based upon fixed geometry and could not be affected without altering the bending radius of the coil. The location of the impact against the forming roll is vitally important to properly form the first wrap.
FIG. 1 shows a more recent prior art set of bending rolls 10 for use in a coil box. The upper bending rolls 12 and 14 are mounted on a pivotable frame 16. The pivotable frame 16 allows for adjustment of the gaps 18 and 20 formed between the upper bending rolls 12 and 14 and a base bending roll 22. A main jackscrew 24 acting against a fixed stop 26 will pivot the main frame 16 about pivot point 28 to change gaps 18 and 20. However, the changes in gaps 18 and 20 are nonequal and nonlinear with this configuration, thus facilitating the need for differentially adjusting bending roll 14 with respect to bending roll 12. To provide for this fine adjustment, an auxiliary jackscrew 30 has been provided to allow for adjustments of upper roll 14 with respect to upper roll 12. The complex prior art arrangement also requires a pair of balance cylinders 32 (only one of which is shown in FIG. 1) and a hold-down cylinder 34 for proper operation.
The object of the present invention is to provide a simpler and more cost-effective method and apparatus for fine tuning the bending roll geometry which will provide appropriate setup for the initial coil formation.